1. Field of the Invention
The present invention is related to a packing method for packing quartz glass or quartz glass base material, which is a base material of optical fibers used for optical communications.
2. Description of Related Art
Quartz glass or a quartz glass base material, which is a base material of optical fibers used for optical communications, is manufactured by sintering and vitrifying soot sediment. The soot sediment can be manufactured by one of vapor-phase axial deposition (VAD) method, outside vapor deposition (OVD) method, and modified chemical vapor deposition (MCVD) method. The glass base material is elongated to a predetermined diameter and then shipped.
If there is a crack on the surface of the glass base material, the optical fiber drawn from the glass base material having a crack will be cut during the drawing. Therefore, much care is needed in order not to damage the surface of the glass base material. Conventionally, glass base material was put into a square-shaped box, and the opening between the glass base material and the box was filled with a cushion for shipping.
Recently, because of the development of the optical fiber communication industry, the demand for quartz glass base material has increased, and the quantity of shipments of glass base material has also increased. A plurality of glass base materials is usually put together into one box to be shipped.
However, if a plurality of glass base materials are packed together in one box, the glass base materials may be damaged because the glass base materials may contact with each other due to the vibration occurring during the transportation of the glass base materials. The cushion is filled in the opening between the glass base material and the box to prevent the glass base material from contacting with each other. However, the conventional square-shaped box has large openings between the glass base material and the box and thus needs a large amount of cushion material. Furthermore, when packing a plurality of glass base materials in one box, if the cushion is made with soft material, the glass base materials inside the box may collide with each other due to the vibration during the transportation. In the worst case, the glass base materials may crack during the transportation.
Therefore, every individual glass base materials must be wrapped with buffer material for packing, such as air packing, which contains air inside. Then, one piece of the glass base material is packed in one box, or a plurality of glass base materials are packed together in one box to prevent cracking and breaking. However, the conventional packing method requires a large amount of buffer material and the box, and thus the conventional packing method has an economic disadvantage. Furthermore, the conventional packing method needs a large amount labor and time for packing. If there is space between the end of the glass base material and the end of the box in the longitudinal direction, the glass base material moves in the longitudinal direction during the transportation. Thereby, the end of the glass base material contacts with the box which may cause a crack or breakage of the glass base material.